So here is what's going on, my computer restarts randomly when I'm playing a game. Sometimes it's an hour into the game, or maybe less. After it restarted, within 3 seconds it restarts itself again in loop, I couldn't even see the mobo BIOS page. The temporary way to bypass this is to switch off the PSU, and then wait for like 5 seconds or so and then turn it on again. Then it will boot the computer just fine. I did a few O/C to the CPU and VGA, it was fine before, I could play games all night long. Just wondering what's going on with my PC. Some compatibility issue probably or might be the O/C that caused all this. Any help would be appreciated. Thanks.

PS: Just now it restarted itself again, I wasn't doing anything at all with the computer. Rebooted the computer and then a few minutes after, it restarted itself.

I disconnected the DVD-ROM and any other cables. the only cables that are connected, power cable, keyboard/mouse and vga. It also restarts while I'm in BIOS. After it restarts itself for the first time, it will keep restarting in loop, can't even see the MB's logo window. When this happens, I switched off the PSU power through the back side.

-Make sure you have the motherboard pegs in the correct spots (sometimes people put on in the wrong spot or one too many).
-Check your heatsink mounting on the CPU. Even the CPU takes a lot of load in the BIOS.
-Clear CMOS.
-Try one stick of RAM, spare graphics card, etc. Process of elimination.